Test: Skin Prick Test - Ragweed

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Background/Purpose

Ragweed pollen usually reaches peak levels in mid-September; this type of pollen can cause seasonal allergic rhinitis (more commonly known as hay fever), which affects as many as 23 million people in the U.S.

There are 17 species of ragweed in the United States. The weeds grow in most regions, typically blooming and producing a fine-powder pollen from August into November.

Symptoms of ragweed allergy are similar to those of other pollen allergies:
Sneezing
Runny nose
Nasal congestion
Headaches
Irritated eyes
Itchy throat

Ragweed pollen can also aggravate asthma symptoms, leading to increased coughing and wheezing.

Procedure

The test area is cleaned and labeled using an appropriate skin marker. When multiple tests are being performed there should be a minimum of of 3cm between them. The skin is pricked lightly and quickly vertically through the sample allergen . A new micro lancet should be used for each substance being tested. The excess sample allergen should be removed immediately with an absorbent paper towel.
The wheals should be read after 15-20 minutes. For a positive reaction, the wheal should be >= 3mm in diameter. A valid result also requires a positive histamine reaction >=3mm and a negative saline control reaction of < 3mm.
Performed: Bilaterally

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Skin prick test of ragweed allergens.

Criteria

• <3mm wheal
• No systemic reaction

Measurement

LOINC Code

Scale/Grading

selection range; grade - LOINC ID
Option - Value option selection range; grade - LOINC IDPass < 3 ; Pass - Equivocal = 3 ; Fail - Fail > 3 ; Fail -